Conventionally, there has been known a metal-oxygen cell comprising a positive electrode that uses oxygen as an active material, a negative electrode that uses a metal as an active material, and an electrolyte layer sandwiched between the positive electrode and the negative electrode and containing an electrolyte solution.
In the metal-oxygen cell, at the time of discharging, in the negative electrode, the metal is oxidized to generate metal ions, and the metal ions are conducted to the electrolyte layer and move to the positive electrode side. Meanwhile, in the positive electrode, oxygen is reduced to generate oxygen ions, the oxygen ions are bonded to the metal ions to generate a metal oxide. In addition, in the metal-oxygen cell, at the time of charging, in the negative electrode and the positive electrode, a reaction reverse to the reaction occurs.
In the metal-oxygen cell, when a metallic lithium is used as the metal, a large charge-discharge capacity can be obtained, because the metallic lithium has a high theoretical voltage and a large electrochemical equivalent. Further, when oxygen in the air is used as the oxygen, the energy density of the cell per mass can be increased, because there is no need to fill the cell with a positive electrode active material.
However, when the positive electrode is exposed to air in order to use oxygen in the air as a positive electrode active material, a problem is that the electrolyte layer, the negative electrode and the like deteriorate due to intrusion of moisture, carbon dioxides etc. in the air into the cell. Then, in order to solve the problem, there is known a metal-oxygen cell comprising a positive electrode containing an oxygen-occluding material that deintercalates oxygen by light-receiving, a negative electrode comprising a metallic lithium, an electrolyte layer sandwiched between the positive electrode and the negative electrode and containing an electrolyte solution, wherein the positive electrode, the negative electrode and the electrolyte layer are sealed and housed in a housing having a light transmission unit configured to guide light to the oxygen-occluding material (for example, see Patent Literature 1).
Furthermore, as a positive electrode material of the metal-oxygen cell, instead of using the oxygen-occluding material that needs light receiving, use of an oxygen storage material capable of chemically occluding oxygen in the inside thereof and releasing oxygen therefrom or capable of physically adsorbing oxygen on the surface thereof and desorbing oxygen from the surface thereof without the need of light receiving is studied.